1. Field of the Invention
The invention relates to a monitoring device for safeguarding a driven element, and an elevator comprising such a monitoring device.
2. Description of Related Art
Elevator doors can become dangerous for a passenger if they are not monitored and there is the risk of the passenger being trapped. This risk is nowadays reduced or even wholly eliminated by means of light barriers, light gratings, active and passive infrared sensors, ultrasonic sensors or else by means of mechanical pressure switches. In many cases, light gratings are used which form a horizontal grating of light barriers. These light gratings consist of a respective transmitting and receiving strip. Both strips are approximately two meter longitudinal slender profiles containing many transmitting and receiving elements generally incorporated in a manner distributed uniformly over the length. What is common to all of the sensor principles, however, is that they are comparatively expensive.